JPH03132694A - Method for housing image data - Google Patents

Abstract

PURPOSE:To effectively utilize a memory space by housing new image data in a free area generated after mixedly housing plural image data having different bit width in a memory. CONSTITUTION:Image data are housed in the address order of a memory plane 1a so that a 1st bit is surely housed in a 1st memory plane 1a. When the hous ing request of an image data group whose picture elements can not be complete ly housed even if the 1st memory plane 1a is used up to its final address is generated, free areas included in a 2nd and subsequent memory planes 1b to 1d are retrieved. When information relating to the free areas is formed at a proper timing, a proper free area can be selected and housed in each housing request of a new image data group. Thus the memory 1 can be efficiently used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image data storage method when image data having different bit widths are mixed and stored in a memory.

(Prior Art) When using an information processing device such as a computer, an operator usually operates a keyboard while viewing an image displayed on a cathode ray tube display or the like. The screen displayed on this display is read from memory. The memory stores image data transferred in advance from a host device and image data edited based on data input from a keyboard. For example, when image data for displaying one pixel consists of 4 bits, and the data is stored in normal random access memory in address order, four types of address signals are generated for each pixel to read it out. Must. In this case,
There is a limit to increasing the speed of continuous output.

Therefore, a method of storing image data as shown in FIG. 2 is adopted.

FIG. 2 is an explanatory diagram showing an example of a memory configured with a plurality of memory planes.

The memory 1 in the figure has four memory planes la.

It consists of lb, lc, and ld. Each memory plane is configured to be able to store IXn bits of data. In the case of a binary image that is simply displayed in black and white, one bit of image data is sufficient to display one pixel. However, in a two-color printed image or a multicolor image with gradation, image data for displaying one pixel is composed of several bits.

For example, assuming that the image data for displaying one pixel consists of four bits, each bit is distributed and stored at the same address A in the four memory planes 18 to 1d, as shown in the figure.

In this way, by generating address signal A once, 4 bits of data can be read out at once. As a result, image data for one pixel can be read out at high speed.

(Problem to be Solved by the Invention) By the way, in information processing equipment that adopts the so-called multi-window method, in which multiple screens are divided or overlapped on the display, there are screens that display black and white binary, and gradation. A screen including a certain image, a screen with multicolor printing, etc. are mixed and displayed. In this case, the image data for displaying each image may have different bit widths.

FIG. 3 illustrates an example of such image data.

That is, FIG. 3(a) shows image data of a black and white binary image;
The same figure (b) is the image data of the two-color printing image, the same figure (
C) and (d) are image data of images with gradation or multicolor printing.

It is not appropriate to store these image data in memories provided separately in advance, since this complicates the circuit configuration and significantly increases the size of the hardware. Therefore, image data having different bit widths are mixed and stored in one memory.

FIG. 4 is an explanatory diagram showing an example of image data after being stored in a conventional memory.

This memory 1 is composed of four memory planes similar to that shown in FIG. Here, 1 pixel is 2
Image data (2) consisting of bits, image data (2) consisting of 4 bits per pixel, and image data (2) consisting of 1 bit per pixel are stored in order. When such a storage method is used, image data can be stored within a range where the total number of pixels of each image data does not exceed the number of pixels that can be stored in the memory.

However, as is clear from Figure 4, for example,
When storing a large amount of image data each consisting of one pixel and one bit, the memory planes lb, lc, and ld other than the memory plane 1a are not used at all, and there is a problem in that the memory usage efficiency as a whole decreases.

The present invention has been made with attention to the above points, and an object of the present invention is to provide an image data storage method that can efficiently use the memory when image data with different bit widths are mixed in one memory. This is the purpose.

(Means for Solving the Problems) The image data storage method of the present invention stores each bit at the same address of a plurality of memory planes constituting a memory when image data for displaying one pixel consists of a plurality of bits. In a device that stores the image data in a distributed manner, the image data with different bit widths are mixed and the first bit is always stored in the first memory plane, and the address of the memory plane is When there is a request to store a group of image data whose number of pixels cannot be stored even if the image data is stored in sequence and the final address of the first memory plane is used, the group of images requested to be stored is When the number of pixels and bit width of the data are recognized and the first bit is stored in the second or lower memory plane, an empty area that can store the above-mentioned group of image data is searched and This data is characterized in that the data is stored in the free area.

(Function) The above method uses the conventional method to mix image data with different bit widths and store them in memory, but when that memory becomes full, the second and subsequent memory planes are Search for available free space. If information regarding this free space is generated at an appropriate timing, an appropriate free space can be selected and stored each time a new group of image data is requested to be stored.

(Example) Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 is an explanatory diagram showing an embodiment of the image data storage method of the present invention.

As shown in FIG. 1(a), in the method of the present invention, for example, there are four memory planes la.

A mixture of image data having different bit widths for displaying one pixel is stored in a memory 1 having lb, lc, and ld.

In this embodiment, the image data to be stored in the memory 1 has contents marked with ■, ■, ■, ■, ■, as shown in FIG. 1(a) to FIG. 1(e). It is data.

FIG. 5 shows the specific bit width and number of pixels of this input image data.

In other words, the image data ■ has a bit width of “2” and a pixel count of “2”.
5" Image data ■ has a bit width of "4" and the number of pixels per pixel is "7" Image data ■ has a bit width of "1" and the number of pixels per pixel is "12" Image data ■ has a bit width of °"2"9
The number of pixels is 4°, and the bit width is 3.
, the number of pixels is "8".

When these data are to be stored in the memory 1 shown in FIG. 1, in the method of the present invention, storage is first started in the conventional manner as previously explained with reference to FIG. That is, the first bit is always stored in the first memory plane 1a, and the image data is stored in the order of the addresses of the memory planes.

The first image data ■ shown in FIG. 1(a) with a bit width of ``2'' and a pixel count of ``5°'' stores the first bit in the first memory plane 1a of the memory 1, and the address is " It is stored between "1" and "5". Then, when storing the next image data ■ as shown in (b) of the same figure,
The first address is the image data stored at the beginning.
The storage for "7" pixels is performed with the 6th address next to the last pixel as the starting address.

In this case, as shown in FIG. 1(b), under the first and second memory planes la and lb in which the image data ■ is stored, the same number of pixels as the first image data ■ is stored. free space will be created.

In order to use this free space for storing new data later, in the method of the present invention, free space information as shown in FIG. 6 is generated.

FIG. 6 is a list showing the contents of free space information.

First, the free space generated under the image data ■ is set to N.
o, 1, the start address is expressed as "1", the number of pixels per pixel is "5", and the bit width is "2".

Next, as shown in FIG. 1(C), the third image data ■ is stored in the memory 1. This image data ■ has a bit width of ``1'' and a pixel count of '12'', which is a relatively large number of pixels. As shown in FIG. 1(C), storage is performed in the conventional manner.

Note that if the image data (3) is stored first, no free space will be created, and therefore no free space information will be generated.

However, when image data ■ is stored, free space is generated again, so as shown in FIG.
As o, 2, start address "13" 1 pixel number "12",
Free area information with a bit width of "3" is generated.

After that, the bit width “2′” number of pixels “5” shown in FIG. 1(d)
Suppose that there is a request to input image data ■ of ``.'' In this case, the number of remaining pixels in the first memory plane 1a of memory 1 is "3," and with the previous storage method, this image data ■ cannot be stored.

Therefore, the free space information shown in FIG. 6 is searched. Then, the number of pixels and bit width of the free area 1 are compared with the number of pixels and bit width of the image data (2). N
The number of pixels in the free area of o, 1 is “5” and the bit width is “2”
Since the number of pixels of image data ■ is "4" and the bit width is "2", this image data ■ is No. 1.
It is determined that storage is possible in the free space of . Therefore,
As shown in FIG. 1(d), image data ■ is stored.

Furthermore, when there is a request to store image data (2), the number of pixels up to the final address of the first memory plane is compared again. In this case as well, it can be seen that the image data ■ cannot be stored as is. Therefore, the free space shown in FIG. 6 is searched again in the same manner as described above.

Incidentally, at the stage when the image data ■ is stored in the free area No. 1, the free area No. 1 is deleted from the free area information. Therefore, the number of pixels and bit width of free area No. 2 and image data (2) are compared. In this case as well, since the bit widths are the same and the number of pixels in the free area is greater than the number of pixels in the image data (2), it is determined that the image data (2) can be stored. Therefore, as shown in FIG. 1(e), the image data ■ is stored.

If the image data is stored as described above,
For each image data, the number of bit widths of 2 pixels and the number of memory planes storing the first bit are made into a table. Image data is read using this table. In this case, control such as outputting a read enable signal only to the memory planes that need to be read can be performed to prevent image data of unnecessary memory planes stored at the same address from being read out at the same time.

For example, in FIG. 1(d), when image data ■ is to be stored, free space information regarding two free areas is generated as shown in FIG. , this image data ■ may be stored. In this case, if image data ■ is stored in free area No. 2, the image data shown in FIG.
) The amount of unnecessary parts increases compared to the example shown in ). Therefore, when there are a large number of empty areas that can store image data, it is preferable to compare and search for empty areas with as close to the number of pixels and bits as possible, and control to store the image data there.

FIG. 7 shows a flowchart showing the specific operation of the method of the present invention. This flowchart specifically represents the procedure for storing image data in the memory, which was explained using FIG. 1 earlier.

First, at the start of storage into the memory, the storage start address of the memory is initialized (step Sl). That is, when the first memory plane 1a is used as a reference, the start address for storage is set to 1''.Then, the first image data is input (step S2).Furthermore, the pixels of the image data The number of pixels is compared with the remaining area of the first memory plane (step S3).If image data with fewer pixels than the remaining area is input,
The process moves to step S4, and image data is stored from the storage start address. This storage is performed in a conventional manner as described above.

After the storage is completed, the storage start address is updated (step S5). That is, when image data with a pixel count of "5" is stored, the storage start address is advanced by "5''. Then, unused space information is generated (step S6). The number of pixels in the unused space is The number of pixels is the same as the number of pixels of the image data stored in the memory, and the bit width is the total number of memory planes of the memory itself minus the bit width of the image data stored immediately before.
The process moves to inputting the next image data again (step S7).

Here, if the number of pixels of the next image data is smaller than the remaining area of the memory, the process moves to step S7, and unused space information is referred to. If there is no unused space, the storage process ends (step S8), but if there is unused space, the bit widths are compared and the number of pixels is compared (step S8).
9 and step S10). If it is determined that image data cannot be stored in one unused space, the unused space information is referred to again and the comparison with another unused space is repeated.

In this way, the processing from step 87 to SIO is repeated to search for an unused space that can be stored.

If unused space that can be stored is obtained, step Sll
, store the image data in the unused space,
After that, update the unused space table (step 5
12). That is, used and unused space information is deleted.

Then, the process returns to step S2 again to input the next image data.

Through the above processing, the unused space in the memory can be effectively used to store other image data.

In the above description, the first memory plane and the first bit of image data do not necessarily have to refer to the first one physically. Therefore, any one of the plurality of memory planes may be selected as the first memory plane.

Further, the free space information may have any content as long as the number of pixels and the number of bits of the image data can be substantially compared.

(Effects of the Invention) According to the image data storage method of the present invention described above, after image data with different bit widths are mixed and stored in memory in the conventional method, the image data that occurs after the storage of these image data is Since new image data can be stored in the free space, memory space can be used effectively. That is, more image data can be stored with the same memory capacity than in the conventional method. As a result, it is possible to reduce the size and improve the performance of the device.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an embodiment of the image data storage method of the present invention, Fig. 2 is an explanatory diagram showing an example of a memory composed of a plurality of memory planes, and Fig. 3 is an example of image data with different bit widths. FIG. 4 is an explanatory diagram showing an example of image data after storage in a conventional memory.
FIG. 6 is a list of the bit width and number of pixels of the input image data shown in FIG. 1, FIG. 6 is a list of free space information, and FIG. 7 is a flowchart showing the specific operation of the method of the present invention. 1...Memory, la, lb, lc, ld-...memory plane, ■~■
...Image data.

Claims (1)

[Scope of Claims] When image data for displaying one pixel consists of a plurality of bits, the image data is stored by distributing each bit to the same address of a plurality of memory planes constituting a memory, Image data with different bit widths are mixed, the first bit is always stored in the first memory plane, the image data is stored in the order of the addresses of the memory plane, and the first bit is stored in the first memory plane. 1, the number of pixels that cannot be stored even if the final address of the plane is used
When there is a request to store a group of image data, the number of pixels and bit width of the group of image data requested to be stored are recognized, and the first bit is stored in the second and subsequent memory planes. An image data storage method comprising: searching for an empty area in which the one group of image data can be stored, and storing the one group of data in the empty area.